class PhusionPassenger::AbstractServerCollection

def synchronize

operation.
the code within the block. The entire block will be a single atomic
Acquire the lock for this AbstractServerCollection object, and run 
def synchronize
	@lock.synchronize do
		yield
		if @next_cleaning_time.nil?
			@collection.each_value do |server|
				if @next_cleaning_time.nil? ||
				   (eligable_for_cleanup?(server) &&
				    server.next_cleaning_time < @next_cleaning_time
				   )
					@next_cleaning_time = server.next_cleaning_time
				end
			end
			if @next_cleaning_time.nil?
				# There are no servers in the collection with an idle timeout.
				@next_cleaning_time = Time.now + 60 * 60
			end
			@next_cleaning_time_changed = true
		end
		if @next_cleaning_time_changed
			@next_cleaning_time_changed = false
			@cond.signal
		end
	end
end